Rigutto Isabel M L, Sburlan Ştefania C, de Bont Lars W P, Berben Tom, de Graaf Rob M, Slomp Caroline P, Jetten Mike S M
Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Nijmegen, the Netherlands.
Department of Earth Sciences - Geochemistry, Utrecht University, Utrecht, the Netherlands.
Environ Microbiol. 2025 Jul;27(7):e70139. doi: 10.1111/1462-2920.70139.
Coastal ecosystems are susceptible to eutrophication and deoxygenation, which may alter their nitrogen cycle dynamics. Here, we investigated the microbial nitrogen cycling potential in the sediment of a seasonally euxinic coastal ecosystem (Lake Grevelingen, NL) in winter and summer. Activity tests revealed ammonium (NH ) oxidation potential with maximum potential rates up to 53 μmol g day, even in anoxic sediment layers. A nitrifying microbial community was present in both oxic and anoxic sediment sections (up to 1.4% relative abundance). Nitrate (NO ), nitrite (NO ), and nitrous oxide (NO) reduction potential were prominent across all sediment sections, with the highest potential rates (167 μmol NO g day) in the surface sediment in summer. Denitrification (79.3%-98.4%) and dissimilatory nitrate reduction to ammonium (DNRA; 1.6%-20.7%) were the major NO removal pathways, as supported by the detection of the narG/napA, nirK/nirS, norB, nosZ and nrfA/otr genes in all sediment sections. The DNRA contribution increased with depth and with the addition of electron donors, such as monomethylamine. Anaerobic ammonium oxidation (anammox) was not detected in these eutrophic sediments. Combined, our results show that there is high potential for nitrogen removal in eutrophic coastal ecosystems, which may help further restoration measures.
沿海生态系统易受富营养化和脱氧作用影响，这可能会改变其氮循环动态。在此，我们调查了冬季和夏季一个季节性缺氧沿海生态系统（荷兰格雷夫林根湖）沉积物中的微生物氮循环潜力。活性测试显示，即使在缺氧沉积层中，铵（NH）氧化潜力的最大潜在速率高达53 μmol g⁻¹ d⁻¹。在有氧和缺氧沉积区均存在硝化微生物群落（相对丰度高达1.4%）。在所有沉积区，硝酸盐（NO₃⁻）、亚硝酸盐（NO₂⁻）和一氧化二氮（N₂O）还原潜力均很显著，夏季表层沉积物中的潜在速率最高（167 μmol NO₃⁻ g⁻¹ d⁻¹）。反硝化作用（79.3%-98.4%）和异化硝酸盐还原为铵（DNRA；1.6%-20.7%）是主要的NO₃⁻去除途径，所有沉积区均检测到narG/napA、nirK/nirS、norB、nosZ和nrfA/otr基因，这支持了上述结论。DNRA的贡献随深度增加以及电子供体（如甲胺）的添加而增加。在这些富营养化沉积物中未检测到厌氧氨氧化（anammox）。综合来看，我们的结果表明富营养化沿海生态系统具有很高的氮去除潜力，这可能有助于进一步的恢复措施。
